Journal of Dental School Shahid Beheshti University of Medical Sciences http://jds@sbmu.ac.ir
Shahid Beheshti University Dental Journal - Journal articles for year 2008, Volume 26, Number 3Yektaweb Collection - http://www.yektaweb.comen2008/12/11Correlation between chronological age and developmental status of third molars (A radiographic evaluation)http://jds.sbmu.ac.ir/browse.php?a_id=414&sid=1&slc_lang=en
<p><strong>Background and Aim:</strong> Determining chronological age of individuals is an investigation key in legal medicine. The aim of this study was radiographic evaluation of correlation between chronological age of Iranian people and developmental status of third molar tooth based on Demirjian staging method. </p><p><strong>Materials & Methods:</strong> This cross-sectional and diagnostic study was accomplished in Radiology department, Dental School, Shahid Beheshti University of Medical Sciences in Tehran (2004-2005). 350 young adults, 15-25 year-old, attended the study. ID cards and radiographic evaluation were used for data collection. The radiographs were studied by a legal medicine resident and an oral and maxillofacial radiologist. Determining the developmental stages of third molar teeth was based on Demirjian method. Statistical calculations were carried out by Levene, t, Wilcoxon's signed rank, Mann-Whitney, Friedman tests and Kendal correlation coefficients (tau-b). </p><p><strong>Results:</strong> The distribution of different development stages of Demirjian method increased by development of third molars. There was a significant statistical discrepancy between boys and girls for the lower left third molar tooth (P<0.001) males were in a higher development rank. According to Calton system, the relation between Demirjian method and age was average in maxillary third molar teeth and was strong in mandibular third molar teeth. The maxillary third molars were generally in a higher development rank compared to mandibular third molar teeth (Friedman test, X2 = 44.214, P<0.001). Among four molar teeth, only developmental stage of lower left third molar was diagnosed to be effective (R= 0.714, R2 = 0.51, adjusted R2 = 0.507, F = 209.047, P< 0.001). </p><p><strong>Conclusion: </strong>Only stage (H) of Demirjian method that the distal canal is closed can be predicted with %99 precision whether the person will be 18 or above 18 years old. </p><p><strong>J Dent Sch 2008 26(3): 1</strong></p>Mitra AkhlaghiComparison of upper molars' movements in use of cervical headgear and pendulum appliance by finite element methodhttp://jds.sbmu.ac.ir/browse.php?a_id=415&sid=1&slc_lang=en
<p><strong>Background and Aim:</strong> The movement of molars has been evaluated in many studies to correct Cl II malocclusion by non-compliance appliances but the results are controversial. The aim of this study was to compare the upper first and second molars' movement in cervical headgear (HG) and pendulum appliance (PEND) by finite element method. </p><p><strong>Materials & Methods:</strong> For modeling process, one of the best dry skulls was CT scanned (1mm slices). Modeling was done according to the mechanical properties of cortical and trabecular bone of maxilla and PDM and teeth and transferred to computer by scanner. Elementing, meshing and loading was done. The magnitude of force for both appliances was 250 gr and line of force for HG was 20 degree above the occlusal plane action and for PEND was along the midlingual surface of upper first molar crown. Tooth movement analysis was performed by the software named Ansys 5.71. </p><p><strong>Results:</strong> The amount of dislocation of the 1st molar cusps tip (mesiobuccal, mesiopalatal, distobuccal, distopalatal) at presence of second molar in bucco-lingual dimension showed distal-in rotation in HG and mesial-in rotation for pendulum. In mesio-distal dimension, the four cusps of 1st molar moved distally in HG and palatal cusps moved more in PEND. In vertical dimension, 1st molar showed extrusion in HG and intrusion in PEND for distal cusps. </p><p><strong>Conclusion:</strong> The presence of second molar had impact on the quality of upper first molar in both appliances and it moved in a distal direction, extruded and buccal drifted in both of them. Therefore, with regard to the cooperation of the patients, pendulum appliance is recommended to correct Cl II malocclusion instead of cervical headgear.</p><p><strong>J Dent Sch 2008 26(3): 2</strong> </p>Allahyar GeramyDetermination of caries condition in undertreatment major Thalassemic children in Tabriz Pediatric Hospitalhttp://jds.sbmu.ac.ir/browse.php?a_id=416&sid=1&slc_lang=en
<p><strong>Background and Aim:</strong> Major β thalassemia is a hereditary hematologic disease with severe clinical symptoms such as certain organic, skeletal and periodontal difficulties and increase of dental caries rate. The aim of this study was to determine the dental caries rate of Thalassemic children and to compare it with the control groups. </p><p><strong>Materials & Methods:</strong> Sixty β thalassemia and healthy children in three groups, 1-5 years group for dmft study, 5-12 years for DMFT and dmft study and after 12 age years for DMFT study were randomly selected. Means of DMFT and dmft and plaque control indices (the brushing and flossing application) were studied in both groups and between three age groups. Comparison of results were made using ANOVA and t. </p><p><strong>Results:</strong> Mean of carious (d,D=4, 5.67) and extracted (m,M=0.22, 0.55) teeth were more in thalassemic patients and mean of filled teeth (f,F=0.45,0.82) were more in control groups. Control group brushed their teeth more frequently and the difference between case and control groups was significant (P<0.05), but there was no significant differences between control and case groups in using dental floss. To summarize, caries rate in both primary and permanent dentition was significantly higher in thalassemic patients comparing to control group (P<0.05). <strong>Conclusion:</strong> Caries rate is high in both primary and permanent dentition in thalassemic patients. However, there are many contributing factors in the rate of caries in thalassemic children but this study determined lack of adequate dental care as a major factor. </p><p><strong>J Dent Sch 2008 26(3): 3</strong></p>Naser Asl Amin AbadiThe effect of inclined bite plane and modified FRII treatment on dentoskeletal changes in Cl II/I malocclusionhttp://jds.sbmu.ac.ir/browse.php?a_id=417&sid=1&slc_lang=en
<p><strong>Background and Aim:</strong> The prevalence of Cl II malocclusion is high in the population. The functional appliances are used in the patient who has mandibular deficiency. The present study was aimed to compare the dentoskeletal changes of CLII/I Malocclusion who used inclined anterior bite plan and modified FRII. </p><p><strong>Materials & Methods:</strong> The material consisted of 30 patients, with Cl II/I malocclusion, ANB > 4º in late mixed dentition. Half of the patients (9 girls and 6 boys) were treated by inclined anterior bite plane and reminder (8 girls and 7 boys) by modified FRII appliance. Lateral cephalogroms were obtained and traced before and after treatment and certain angular and linear variables were measured. The pretreatment and post-treatment measurements were compared using Mann-whitney U test and Wilcoxon Test to evaluate the significancy of the results. <strong>Results: </strong>Significant changes mainly caused by mandibular growth, were observed after treatment by modified FRII and inclined anterior bite plane. This study indicated no statistical significant differences between two groups except Ar-B and AR-Pog. </p><p><strong>Conclusion:</strong> Considering the less bulky anterior inclined bite plane and its easier construction we can use this appliance instead of modified FRII.</p><p><strong>J Dent Sch 2008 26(3): 4</strong> </p>Shahin Emami MeibodiDiagnostic values of conventional radiography and digital subtraction radiography in detection of periapical bone lesions (An invitro study)http://jds.sbmu.ac.ir/browse.php?a_id=418&sid=1&slc_lang=en
<p><strong>Background and Aim:</strong> The detection of the teeth periapical lesions is associated with some problems clinically. As this diagnosis is based on the observation of radiolucent regions in the periapical area, the radiographic assessments of the lesions are important. The aim of the present study was to evaluate the diagnostic values of conventional and digital subtraction radiography to improve the diagnostic ability of periapical lesions. </p><p><strong>Materials & Methods:</strong> Artificial bone lesions in the periapical region of 15 teeth were created. Conventional and digital radiography were taken of all specimens in four stages: preoperative and after lesion creation in cancellous bone by using No.2, No.6 and No.10 slow speed steel burs. Digital radiography images were exposed where as the distance between x-ray source and CCD was 24 cm and position of tube, teeth and receptor was fixed. The data was analyzed by kappa statistics. </p><p><strong>Results:</strong> Diagnostic sensitivity in detection of lesion by conventional radiography and digital subtraction radiography by using bur No. 2 were 34.5%, 71.4%, No. 6 were 54.7%, 95.2% and bur No.10 slow speed steel bur were 92.9%, 100% respectively. </p><p><strong>Conclusions:</strong> The digital subtraction radiography in comparison with conventional radiography had a higher diagnostic value in detection of periapical bone lesions. </p><p><strong>J Dent Sch 2008 26(3): 5</strong></p>Mahshid MobiniThe effect of post type on stress distribution in endodontically treated maxillary central incisors: A Finite Element Studyhttp://jds.sbmu.ac.ir/browse.php?a_id=419&sid=1&slc_lang=en
<p><strong>Background and Aim:</strong> Following endodontic therapy, teeth need to be protected from fracture. The likelihood of fracture depends on the type of restoration. This simulated study was designed to compare the effect of two different restorations on stress transmission to dental tissue. </p><p><strong>Materials & Methods:</strong> Four 3-dimentional models of maxillary central incisor were created as following by finite element analysis: (1) Restored with prefabricated stainless steel post, composite core and full ceramic crown (IPS Impress2), (2) restored with prefabricated Fiber glass post, composite core & full ceramic crown (IPS Impress2), (3) restored with Accessory Fiber glass post, composite core & full ceramic crown (IPS Impress 2) and (4) without restoration. Each of the models received 100 loads to incisal edge at an angle of 45 degrees to tooth long axis .Von Mises Stress analysis was performed for each model, comparing maximum stress intensity observed. </p><p><strong>Results:</strong> In all groups the greatest stress was observed in the cervical region. The stress increased steadily from apex to C.E.J and decreased from C.E.J to incisal edge. The Von Misses Stress in CEJ was highest in Accessory pin group to compared the other groups. Prefabricated stainless steel post, Fiber Glass post& vital tooth groups showed slight differences in CEJ stress. </p><p><strong>Conclusion:</strong> In all groups the greatest stress was observed in the cervical region. It seems the use of Fiber glass posts in weakened anterior teeth acts better than accessory fiber glass post. </p><p><strong>J Dent Sch 2008 26(3): 6</strong></p>Allahyar GeramyEffect of sugars and carbonated drinks' consumption on anthropometric indices and dental healthhttp://jds.sbmu.ac.ir/browse.php?a_id=420&sid=1&slc_lang=en
<p><strong>Background and Aim:</strong> Carbohydrates are the main source of human diet. More than 60% of total needed energy is obtained from them.Many studies have shown that obesity and dental caries increase with high consumption of sugars and carbonated drinks. Some studies showed that this kind of diet has not any role on obesity and dental caries. The aim of this study was to assess the role of sugars and soft drinks on the anthropometric and dental health indices. </p><p><strong>Materials & Methods:</strong> By a descriptive cross-sectional study in year 1383, a total of 788 healthy 7-years old primary school children were selected via a cluster sampling in Tehran. Their general information was asked from their mothers. 24-hour frequency consumption of sugars including beverge was asked by the trained interviewers via a standard questionnaire. Then anthropometric measurements were also taken for each child. Dental health indices were measured by two trained dental hygienist. The Chi-square and Spearman tests were used for detection of statistical associations. </p><p><strong>Results:</strong> Spearman statistical test did not show any significant relationship between dmft and consumption of sugars and soft drinks. Also consumption of sugars in children who had a problem with height for age and weight for height was higher but they did not show statistical difference. Also consumption of sugars in children who had problem with weight for age was significantly higher (P=0.002). </p><p><strong>Conclusion:</strong> Consumption of sugar in low weight children was higher and there was not any significant relationship between sugar consumption and dmft.</p><p><strong>J Dent Sch 2008 26(3): 7</strong> </p>seyyed Jalal PourhashemiEvaluation of antimicrobial effects of different calcium hydroxide preparation methods with direct exposure testhttp://jds.sbmu.ac.ir/browse.php?a_id=421&sid=1&slc_lang=en
<p><strong>Background and Aim:</strong> Calcium hydroxide has a pronounced antimicrobial activity against most of the bacterial species found in the root canal and now is widely used as an intracanal medicament in endodontic therapy. The aim of this study was to evaluate the antimicrobial effect of different calcium hydroxide preparations with Normal saline, Lidocaine 2%, Chlorhexedin 2% and 0/2%, Iodine Potassium Iodide 2% and Glycerin on Entrococcus faecalis with direct exposure method. </p><p><strong>Materials & Methods:</strong> For conducting this experimental in-vitro study 375 sterile paper points were contaminated with the microbial suspension of Entrococcus faecalis. The samples were placed in sterile dishes and covered with creamy mixture of six different calcium hydroxide preparations. After 1, 3, and 7 days the paper points were immersed in test tubes containing BHI. Microbial growth was evaluated by turbidity in culture mediums. </p><p><strong>Results:</strong> Data obtained showed that all of tested materials had perfect antimicrobial action but only in calcium hydroxide with Chlorhexidine 2% and 0.2% groups perfect antimicrobial action and no microbial growth was observed after 24 hours. </p><p><strong>Conclusion:</strong> Regarding the results of this study it is concluded that the vehicle of calcium hydroxide has not any significant effect on its antimicrobial activity, however, more studies on the effect of vehicles of chemical properties of calcium hydroxide such as its diffusion in similar conditions of root canal system, are needed. </p><p><strong>J Dent Sch 2008 26(3): 8</strong></p>Mahdi TabrizizadehClinical success rate of mineral trioxide aggregate pulpotomy in primary teethhttp://jds.sbmu.ac.ir/browse.php?a_id=790&sid=1&slc_lang=en
<p><strong>Background and Aim:</strong> Formocresol (FC) is yet, the most common medication used for pulpotomy of primary teeth. However, its potential hazards including toxicity, mutagenicity and even some degrees of carcinogenicity are the remaining sources of concern to clinicians. This investigation was aimed at comparing the clinical success level of MTA (case) treated pulps of primary teeth to that of Formocresol (control). </p><p><strong>Materials & Methods:</strong> A group of 17 children aged 4-9 years were selected from those attended Shahid Beheshti, Dental School. Each case was served as case and control (for a matched paired teeth plan). Pre and post operative X-ray (PA or BW) were also obtained in intervals of immediately before, and 6 months after the treatment associated with through clinical assessment of each tooth using clinical soundness criterias. Collected data were analyzed using Mc Nemar test. </p><p><strong>Results:</strong> In total, 40 primary teeth (22 second primary molars and 18 First primary molars) were included in this trial. Statistical analysis of the data revealed no significant difference between clinical or radiographic observation of the groups in 6 month control stage. There was, however, a significant difference between the two groups for their furcation lesions being seen with a higher rate in the case of formocresol treated (control) group in 6 month follow up stage (P=0.047). </p><p><strong>Conclusion:</strong> It seems that clinical and radiographic success level of MTA is as acceptable as formocresol giving the suggestion of its potential replacement for a safer pulp treatment of primary teeth.</p><p><strong>J Dent Sch 2008 26(3): 9</strong> </p>Mahdi RanjpoorComparison of smear layer removal of root canals with citric acid and EDTA- NaOCl (A SEM study)http://jds.sbmu.ac.ir/browse.php?a_id=422&sid=1&slc_lang=en
<p><strong>Background and Aim:</strong> The smear layer is a thin layer composed of organic and inorganic debries which forms on canal walls. Removal of this layer after instrumentation is critical for adaptation between filling material, root walls and apical seal. The aim of this in vitro study was to determine the effect of 30% citric acid and 17% EDTA- 5.25 % NaOCl on smear layer removal in the middle third of root canals. </p><p><strong>Materials & Methods:</strong> In this experimental study, twenty extracted anterior teeth were used. After decoronation, instrumentation was done. The teeth were divided into three groups. After final preparation the canals were irrigated by 10 ml 30 % citric acid in group 1 and 10 ml 17 % EDTA followed by 5.25 % NaOCl in group 2. In control specimens, normal saline was used. Then the roots were split longitudinally and studied under scanning electron microscope. The photomicrographs were evaluated by X and Y methods. The data was analyzed by Kolmogorov-Smirnov, Leven’s, Mann Whitney U and T-student tests. </p><p><strong>Results:</strong> Canal walls were covered with smear layer in the positive control group. In both methods (X,Y), the result showed that canals irrigated with 17% EDTA- 5.25% NaOCL had less smear layer throughout the canal than group irrigated with 30 % citric acid. This difference was not statistically significant in both (X,Y) methods. </p><p><strong>Conclusion:</strong> Both 17% EDTA-5.25% NaOCL and 30% citric acid removed the smear layer from root canal walls effectively. </p><p><strong>J Dent Sch 2008 26(3): 10</strong></p>Maryam Zare JahromiThe effect of premolar extraction on lips' curvatures in borderline orthodontic patientshttp://jds.sbmu.ac.ir/browse.php?a_id=423&sid=1&slc_lang=en
<p><strong>Background and Aim:</strong> Although orthodontists have long recognized that the extraction (Ext) of premolars often is accompanied by changes in the soft tissue profile, investigations indicate that the soft tissue does not always respond favorably to hard-tissue retraction. This study was designed to evaluate the effects of treatment, with and without premolar Ext, on the lateral facial profiles of borderline patients with particular reference to the curvature of the upper and lower lips. </p><p><strong>Materials & Methods:</strong> Eighty-nine border line patients were included in this study. 41 patients were treated with a non-extraction (Non-Ext) protocol, 16 patients were treated with extractions of 5/5, 18 patients with 4/4 and 14 patients with 4/5. All pre-and posttreatment lateral cephalograms were traced and analysis by one examiner. To quantify the soft tissue effects of growth and treatment, the depths of the upper and lower lip curves were calculated in two ways relative to the PM reference line and anterior soft tissue reference line. </p><p><strong>Results:</strong> The changes in depth of upper and lower lip curves were statistically significant (P<0.001). The Non-Ext group showed an increase in depth of upper and lower lip curves, whereas the Ext group showed a decrease in depth of upper and lower lip curves. No significant differences were found between the various extraction sequences (5/5, 4/4, 4/5) for depth of the upper and lower lip curves changes. </p><p><strong>Conclusions:</strong> 1) The upper and lower lip changes were significant more retrusive in the Ext group and more protrusive in the Non-Ext group. 2) There were no significant post treatment differences in the depths of upper and lower lip curves between premolar extraction sequences.</p><p><strong>J Dent Sch 2008 26(3): 11</strong> </p>Hassanali ShafieeComparison of infradental nerve response to inflamed pulp after local application of Lidocaine and Lidocaine plus Morphine in catshttp://jds.sbmu.ac.ir/browse.php?a_id=424&sid=1&slc_lang=en
<p><strong>Background and Aim:</strong> Failure to obtain adequate anesthesia in teeth with inflamed pulps has been known as a clinical symptom for dentists. The aim of this study was to determine the infra-alveolar nerve response to supplementary injected morphine to Lidocaine in anesthetizing teeth with inflamed pulps. </p><p><strong>Materials & Methods:</strong> Thirty mandibular canine in 15 cats were exposed in order to become inflamed. The inferior alveolar nerve was exposed and the recording electrodes were placed upon it while the stimulating electrodes were placed on the teeth. By stimulating the teeth using the stimulator in different voltages, all the received nervous responses were recorded by means of an oscilloscope unit. If the fibers were not blocked a Lidocaine injection, supplementary injection with morphine was used and responses were recorded again. The data were analyzed by t- test. </p><p><strong>Results:</strong> In teeth with inflamed pulps both morphine and/or Lidocaine had significant local anesthetic effects. Lidocaine and morphine acted quite similar and blocked the second group (c) fibers more rapidly and strongly than the first group (A delta) fibers. Supplementary injection of morphine in those cases in which Lidocaine failed to block the first group fibers raised the stimulation threshold and decreased the wave peak and the speed of the first group fibers (p>0.05). </p><p><strong>Conclusions:</strong> Pulpal nerves received morphinergic receptors during inflammation and resisted to the Lidocaine and became anesthetized after supplementary injection of morphine. Using morphine as an adjunct to Lidocaine may complete the anesthetic effect on neurons in inflamed pulps.</p><p><strong>J Dent Sch 2008 26(3): 12</strong> </p>Mir Abdollah SolutiKnowledge and attitude of Tehran high school students on HIV/AIDS, 2005http://jds.sbmu.ac.ir/browse.php?a_id=425&sid=1&slc_lang=en
<p><strong>Background and Aim:</strong> Due to lack of access to information regarding AIDS and its prevention methods, this study assessed the knowledge and attitude of high school students in districts 6 and 11 in Tehran – 2005. </p><p><strong>Materials & Methods:</strong> In this cross–sectional study, 990 high school students selected by multi–step random sampling method were evaluated by NCHS questionnaire including 22 queries about knowledge and the remainder regarding attitude. Data were analyzed by Stepwise multivariable regression, Student's T and Mann – whitney tests. </p><p><strong>Results:</strong> Nine hundred and ninety individuals (538 males and 452 females) participated in the study. 22.5% answered correctly to 5 out of 7 questions concerning the ways not resulting to transmission the disease. The least knowledge was related to the lack of possibility of disease transmission through insect bite. Regarding treatment modalities of AIDS, the students had few information about medications prescribed to prolong the survival time of the patients. 53.5% emphasized the necessity for AIDS screening like routine tests. 77% believed that they were able to protect themselves against HIV infection. 66.6% of subjects were afraid of being affected by the disease. The most popular source of awareness was found to be TV and the least one was radio. </p><p><strong>Conclusion: </strong>The knowledge of high school students of districts 6 and 11 of Tehran students regarding HIV infection was good. Meanwhile promotion from first level to higher levels of high school correlates to increased awareness.</p><p><strong>J Dent Sch 2008 26(3): 13</strong> </p>Ziba MalekiPyknodysostosis -- A case report with a brief review of the literaturehttp://jds.sbmu.ac.ir/browse.php?a_id=426&sid=1&slc_lang=en
<p><strong>Background and Aim:</strong> Pyknodysostosis is a rare sclerosing bone disorder that has an autosomal dominant trait. It is characterized by short stature, brachycephaly, short and stubby fingers, open cranial sutures and fontanel, and diffuse osteosclerosis, where multiple fractures of long bones and osteomyelitis of the jaw are frequent complications. A case is presented which has the characteristic oral and radiological findings that are consistent with this syndrome, along with a brief review of the literature. </p><p><strong>Conclusion:</strong> As oral manifestations and appearance characteristics seen in this disorder are reliable signs for its further examinations, knowing about these signs would be helpful in the diagnosis as well as the improvement of its prognosis. Accordingly, by knowing the oral symptoms and appearance characteristics of the disease, dentist could be the very first person who would look for the necessary examinations led to the diagnosis of the disease. </p><p><strong>J Dent Sch 2008 26(3): 14</strong></p>Roshan RoshannejadAn in vitro comparative study of film thickness of five root canal sealershttp://jds.sbmu.ac.ir/browse.php?a_id=427&sid=1&slc_lang=en
<p><strong>Background and Aim:</strong> An adequate film thickness is an important property of an endodontic sealer, when used in combination with gutta-percha, ensuring an hermetic three- dimensional root canal obturation. Film thickness also affects the sealing ability of sealers. The aim of the present study was to compare the film thickness of the following five root canal sealers: RSA, Topseal, 2Seal, AH26 and Acroseal in Islamic Azad University at 2006. </p><p><strong>Materials & Methods:</strong> In this experimental study all root canal sealers were mixed following mixing procedures advised by manufacturers. A small amount of sealer was placed between two glass plates and a load of 200 gr was applied vertically on the top glass plates for 10 minutes. After setting, the thickness of sealers was measured with a set of digital calipers accurate to 0.01mm. The procedure was repeated ten times for each sealer (n=10). The all data were analyzed by One-way ANOVA and Tukey HSD tests. </p><p><strong>Results:</strong> The mean film thickness (mm) were respectively: AH26=0.36±0.020, Acroseal=0.37±0.019, Topseal= 0.41±0.014, 2Seal=0.38±0.014, RSA=0.040±0.018. AH26, 2Seal and Acroseal showed the best results, but differences among the three groups of sealers were not statistically different. RSA and Topseal showed the highest film thickness and a statistically significant difference was noted among these sealers and the others, but difference among RSA and Topseal was not statistically different. </p><p><strong>Conclusion:</strong> All root canal sealers had acceptable film thickness, but AH26 showed the least film thickness.</p><p><strong>J Dent Sch 2008 26(3): 15</strong> </p>Arjang FallahdoostMicroscopic assessment of the effects of chemoradiotherapy on normal oral mucosa in patients with head and neck cancerhttp://jds.sbmu.ac.ir/browse.php?a_id=428&sid=1&slc_lang=en
<p><strong>Background and Aim:</strong> There are only few studies about effect of chemoradiotherapy based on cellular level. The aim of this study was to evaluate the effects of such treatment on normal cells of oral mucosa. </p><p><strong>Materials & Methods:</strong> Seventy patients whose normal oral mucosa was exposed to radiation during the course of chemoradiotherapy were selected. Before starting the treatment, 2 slides from the normal oral mucosa were prepared for each patient, one from keratinized and one from non keratinized mucosa. At the end of treatment 2 other slides were taken from the same area too. After observing the slides under light microscope in blind form, the results of the observation from the first slides were compared with the results of the second one. Statistical analysis was carried out by Mc Nemar, Marginal Homogeneity and Wilcoxon tests. </p><p><strong>Results:</strong> The results revealed changes in nucleus and cytoplasm, and N/C ratio, formation of bizar cells, cellular abnormality, nucleous and cytoplasmic vacuolization in affected cells during treatment. There was statistically significant differences between the groups (p<0.001). Keratinization of basal cell mucosa in cytology slide was observed after treatment (P<0.01) and also there was an increase in number of inflammatory cells (p<0.001). Cellular apoptosis, numerous granular cells with large size granules, cells with multiple nucleous and clear nuclei, bacterial colony and candida were observed after treatment. </p><p><strong>Conclusion:</strong> chemoradiotherapy may induce formation of bizar cells, abnormal nucleous and cytoplasm, changes in N/C ratio, Cellular abnormality, and cellular vacuolization. </p><p><strong>J Dent Sch 2008 26(3): 16</strong></p>Fatemeh Mashhadi AbbassComparison of one & two visit treatment of open apices with Mineral Trioxide Aggregate plughttp://jds.sbmu.ac.ir/browse.php?a_id=429&sid=1&slc_lang=en
<p><strong>Background and Aim:</strong> Mineral trioxide aggregate (MTA) usually produces moisture by paper cone for at least 4 hours with regard to some studies that the moisture of periapical tissues is enough to set the MTA. The aim of this study was comparison of one-visit apexification with two-visit apexification using MTA plug. </p><p><strong>Materials & Methods:</strong> In this experimental study 70 extracted single-rooted human teeth were selected. The crowns and 2mm of apices were cut. Canal preparation was performed to ISO size No.100 in the apical portion. The teeth were randomly divided into 2 experimental groups of 25 and 2 control groups of 10 teeth. The canals in group one were obturated immediately after MTA plug placed. In group two after placing MTA plug, a moist paper point was placed inside the canal, and after 24 hours, canals were obturated. The roots were covered with two layers of nail polish in the designed system and were transferred in a sterile BHI (Brain Heart Broth) culture. A fresh solution of Enterococcus faecalis was injected to the system every 3 days. For 90 days, the time of culture contamination was registered. Survival analysis with Kaplan-Meier method & Log Rank test were used to analyze the data. </p><p><strong>Results:</strong> Mean and 95% CI of survival time in one visit group was 12.77 (0-25.69) days and in two visit group was 4.16 (1.3-7.01) days. There was no significant difference in survival curve between the two groups. </p><p><strong>Conclusion:</strong> Results showed that apexification in one visit by placing an apical plug of MTA is a predictable and reproducible clinical procedure.</p><p><strong>J Dent Sch 2008 26(3): 17</strong> </p>Behnaz Barakatein